td62 Posted June 3 Share Posted June 3 Hi all I'm new here I have a dt125mx 1981 it idles perfectly revs clean on the side stand, pulls away fine but then stutters and vibrates on part throttle and cruising along it is the same, if I open the throttle all the way it sorts it's self out and accelerates fine, if I move the needle all the way up it gets worse so I lowered it which is slightly better but not much I have tried everything I can think of to sort the running issues out I have, Rebuilt the engine top and bottom new everything. New Carb just to eliminate the old carb Rebuilt the original mikuni checked the float height, same running issue with both carbs. Idle jets I have tried 22.5(std) 25 27 30 Moved the needle to every position all the way up makes it worse (clip down) Flushed the tank (running e5) New ignition coil New plug Checked oil pump Checked for air leakage Exhaust is clear New air filter Chain and sprocket set Cleaned up the earth points and checked each plug for corrosion New battery Battery charging fine Checked timing is set correctly Can anyone help me please? Quote Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted June 3 Moderator Share Posted June 3 Is it burning oil? P.S. I've removed the duplicate post... Quote Link to comment Share on other sites More sharing options...
NE0 Posted June 4 Share Posted June 4 So I assume with all these new parts , including the plug, its been set to the right gap and not just used straight out of the packet? having said that you say it runs at higher revs when you open the throttle, but not so good at lower revs. i can't see it being related to the plug but a higher reving bike at throttle will be glowing nicely and burning fuel correctly, at lower revs it will be cooler (not much I admit) but it's a possibilty. On the basis that the electrics are working as they should, afterall you sound like its had it all replaced, coil, plug, etc, I doubt its the plug cap, as they either work or they don't, but again, its worth a check to rule it out. I think therefore the likely culprit is going to be fuel related. and when I say fuel I include its delivery AND its air/fuel ratio. which carb are you now using , the old one or the new one? Is the carb the correct one in the first place? are you satisfied the old carb is the OEM that came with the bike when new. This would be one of my first questions. Devils advocate here...its not a 175 carb on a 125 is it? Quote Link to comment Share on other sites More sharing options...
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